When I collected my Kodiaq, just before the lockdown, I changed the wheels and tyres from the 19-inch 50-section tyres to 17-inch 65-section (all-season, if that matters). Looking in the fuel filler flap, I see a list of recommended tyre pressures for the three different wheel sizes ie 17, 18 and 19 inch. But.... they're identical at 2.4 bar (35 psi). I find this strange: the 215/65 R17 tyres have a larger volume, so I would expect a lower recommended pressure. 

 

As background, in the cycling world, we're all aware that narrow low-volume road tyres are run at very high pressure, often  in excess of 100 psi. But at the other extreme, 'fat bikes' (with 'balloon' tyres at 4 inches wide or greater) are run at 5 psi, and typical mountain bike tyres 2 - 3 inch wide are run at 15-30 psi, give or take depending on terrain, rider weight and preference. Indeed, according to what I read, a rough guide is that the recommended pressure is inversely proportional to the tyre volume. If so, for the 215/65 R17 tyres, the recommended pressure would be about 30 psi.

 

Indeed, when the wheels/tyres were changed, the fitters, being good conscientious people, inflated the new tyres to the recommended 35 psi. Driving back home, I was more aware of the road surface vibrations filtering through - and this was on all-season tyres (Michelin CrossClimate +) which I know from experience have a very compliant and quiet ride. So something not as expected. Of course, I'm not driving much now in this our Plague Year, but have had a quick experiment lowering the pressure to 32 psi and noting the noticeable improvement, but little data on which to base my (subjective) impressions. Indeed, in my previous car, (VW Golf estate) VW's recommended pressure was very high - 42 psi or 38 for 'comfort' setting. I generally ran the tyres at 32-34 psi, no obvious fuel consumption penalty, no uneven wear, much better ride, no strange steering feel.

 

I would be grateful for any input on this, please - have any of you forum members deviated from the recommended tyre pressures? What did you want to achieve, and did it work out OK? Thanks.....

I run my 215x65x17 winter tyres at 36-37 psi with no untoward ride or handling issues.

On my previous Yeti I found that the higher sidewall profile winter tyres made the handling a bit jelly like and squirmy unless the pressures were increased a bit and the Kodiaq is the same.

Edited 21 April, 20206 yr by Kenny R

Thanks Kenny - I didn't anticipate problems as such, just puzzled where Skoda's recommended pressures come from: they seem to be unnecessarily high for the larger-volume tyres 

@SinglePointSafety

Bicycles really do not have anything to do with it.

Re Fat Bikes of which i have a few and Plus tyre bikes and road bikes.

I might well run the 4.0 x 26 or 4.6 x 26 @ 5-10 PSI on Sand / Snow but still put them to 30 PSI for the road.

Same with the 2.8 or 3.0 x 27.5's maybe 15 psi for offroad and 35 PSI onroad. 

As to road bikes the higher pressures are not due to lower volume, more to rim and tyre type and use. 

 

I run cars of the same weight with maybe 15" wheels and higher profile tyres at the same pressures as i might when 17" wheels are on with lower profile tyres and the same circumference / rolling diameter.

 

Fat Bike and Michelin Cross Climates in 265/65 R 18. in the same picture.  

 I run these CrossClimates at the same pressure as when the wheels have on 285/55 R 18 Tyres on.

Edited 22 April, 20206 yr by Roottootemblowinootsoot

Beg to disagree ref bike tyres: many articles on eg Bike Radar web site and others on tyre compliance for different loads/terrain etc as a function of volume, and as a physicist/mathematician/engineer (yes, I do all of this in my day job) the arguments have some scientific merit. The comparison within the bike world is entirely valid because the one constant is rider mass (perhaps a factor of 2 variance for most bike riders?) and the very wide range of tyre volumes. On the same trail conditions the ride/handling would be abysmal if I didn't adjust bike tyre pressures for different sizes = volumes.

 

Once again, I'm not disagreeing with your point about being able to run car tyres at pretty much any pressure (within reason) without obvious handling/ride problems, but I remain puzzled regarding the criteria used by Skoda to recommend the same tyre pressure across all sizes. After all, the space saver spare has a recommended pressure much higher because..... it is a narrower, smaller-volume tyre.

We will have to disagree then seeing as i have the various bikes and ride them and do a few thousand miles a year on them.

I love science and physicists / mathematicians / engineers, especially those that get out on their bikes and ride them and not just sit with a slide rule and a calculator.

?

Have you posted in the Cycling section yet?

 

Put your Spare Tyre high incase it is ever needed, and you can let it down easier than pump it up if needed.

Same when wondering about tyre pressures, pump towards the ECO setting, then by trial and error you can lower the pressure until you are happy.

That is advice from a Time Served Motor Engineer that did lots of tyre fitting in the past.

Edited 22 April, 20206 yr by Roottootemblowinootsoot

There's a cycling section? And I also ride a few thousand miles a year on a range of bikes (commuting and mountain biking). But, honestly, I'm not trying to score points, I'm really just wondering exactly what process Mrs Skoda (and the other manufacturers) use to estimate optimum tyre pressure. Must be a bit hit-and-miss, for example my Michelin CC+ are rated XL which means a slightly stiffer and more robust sidewall, so the optimum for these might be slightly different for a non-XL tyre

 

And as a fellow cyclist.... stay safe on the roads! I've noticed with the quieter roads, vehicle average speed has increased very significantly ("yeah, well officer, there was nothing on the roads, really quiet, apart from the cyclist I hit.")

Earlier post, I did indeed experiment with my Golf pressures, started out at VW's insanely-high 42 psi recommendation (no doubt to achieve that extra 1 mpg for the official tests), ended up at low-30s, much better ride, much quieter, no discernible fuel penalty. Thanks for the tip ref spare TP, I do indeed over-inflate it for just that reason (because punctures always happen when it's dark and wet and inconvenient).

The Cycling Section is above the General Automotive Chat Section.

 

Much importance with  tyres and use and sidewalls, load and speed rating for a SUV.

XL / Reinforced, and Winter / All Weather, All Season & CrossClimates, Summer & Wet weather tyres.

You notice the difference in the sidewalls when fitting them.  Some are pretty pliable and some are not, and low profile that are not XL can easily damage as can 

something like 'All Seasons from Maxxis like a AP2.

 

I have Cross Climate SUV's which are a different sidewall from other CrossClimates which i have also had on cars.

Edited 22 April, 20206 yr by Roottootemblowinootsoot